262 Mr. Stodart and Mr. Faraday 
kinds when in intimate mixture or in combination, which 
may lead to clearer and more perfect ideas on this subject. 
If two pieces, one of steel, and one steel alloyed with pla- 
tina, be immersed in weak sulphuric acid, the alloy will be 
immediately acted on with great rapidity and the evolution 
of much gas, and will shortly be dissolved, whilst the steel 
will be scarcely at all affected. In this case, it is hardly pos- 
sible to compare the strength of the two actions. If the gas 
be collected from the alloy and from the steel for equal in- 
tervals of time, the first portions will surpass the second 
some hundreds of times. 
A very small quantity of platina alloyed with steel confers 
this property on it : increased the action considerably ; 
with and r ~ it was powerful ; with 10 per cent, of pla- 
tina it acted, but not with much power ; with 50 per cent, the 
action was not more than with steel alone ; and an alloy of 
90 platina with 20 steel was not affected by the acid. 
The action of other acids on these alloys is similar to that 
of sulphuric acid, and is such as would be anticipated : dilute 
muriatic acid, phosphoric acid, and even oxalic acid, acted on 
the platina alloy with the liberation of more gas than from 
zinc ; and tartaric acid and acetic acid rapidly dissolved it. In 
this way chalybeate solutions, containing small portions of 
protoxide of iron, may be readily obtained. 
The cause of the increased action of acids on this and similar 
alloys, is, as the President of this Society suggested to us, 
probably electrical. It may be considered as occasioned by 
the alloying metal existing in such a state in the mass, that 
its particles form voltaic combinations with the particles of 
